CI: Update test job to macos-14 (Apple Silicon)

[RytoEX]

Description

CI: Update test job to macos-14 (Apple Silicon)

Follow-up to c71bbf7.

Motivation and Context

Tests should probably run on the same runner version as build. The macos-14 runners are also faster and seem less error prone.

How Has This Been Tested?

It hasn't.
I ran a test run on my fork's master branch and this seemed to go fine.

Types of changes

• Tweak (non-breaking change to improve existing functionality)
• Performance enhancement (non-breaking change which improves efficiency)

Checklist:

• My code has been run through clang-format.
• I have read the contributing document.
• My code is not on the master branch.
• The code has been tested.
• All commit messages are properly formatted and commits squashed where appropriate.
• I have included updates to all appropriate documentation.

[RytoEX]

I ran a test run on my fork's master branch and this seemed to go fine.